Large Universe Attribute-based Encryption with Multiple Authorities and Outsourced Decryption for Fog-enabled Internet of Things

Designers and users of Internet of Things (IoT) applications where data is stored in a cloud server may have concerns about the cloud’s honest-but-curious problem. Hence, to provide data confidentiality and fine-grained access control, Ciphertext-policy Attribute-based Encryption (CP-ABE) has been widely used to secure and distribute IoT data outsourced to the cloud. However, diverse security, efficiency, and scalability requirements must be satisfied for CP-ABE schemes to suit the IoT environment. This paper presents a CP-ABE scheme for fog-enabled IoT, which includes multiple attribute authorities to avoid the key escrow problem, is designed as a large universe construction to reduce the number of the system’s public parameters, and most of the decryption overhead is outsourced to fog nodes. In addition, our scheme is defined over asymmetric pairings demonstrated to be safer than symmetric ones (used in most existing approaches). The analysis of our proposal and experimental results show its storage and computation efficiency for three security levels recommended in standards.